Method for controlling transmit power for communication system

ABSTRACT

The present invention provides a transmit power controlling method for reducing an influence of incorrect control in a mobile communication system in the CDMA mode. 
     A likelihood of transmit power controlling signal is generated on the basis of the transmit power controlling signal transmitted by a radio base station and the receiving quality, a variation amount of the transmit power is generated on the basis of the likelihood, and the transmit power of a mobile station is controlled on the basis of the variation amount.

TECHNICAL FIELD

The present invention relates to a method for controlling transmit powerin a mobile communication system, more particularly, a method forcontrolling transmit power in a mobile communication system to which acode division multiple access (CDMA) mode is applied.

BACKGROUND OF THE INVENTION

In the CDMA mode, a plurality of mobile stations share a same frequencyband to communicate with a base station. Therefore, in the case of acommunication between a mobile station A and a base station, forexample, a signal from another mobile station B to the base station (anundesired signal) interferes a signal sent from the mobile station A tothe base station (a desired signal) to obstruct a communication betweenthe mobile station A and the base station. Similarly, the signal sentfrom the mobile station A obstructs a communication between the mobilestation B and the base station.

The interference level increases relative to a receiving level of anundesired signal wave received by the base station. The receiving levelof the undesired signal is relative to the transmit power at the timethe undesired signal is sent from a mobile station. Thus, it isnecessary for the base station to control the transmit power from mobilestations so that the receiving level in the base station should bealways minimum essential, in order to keep the interference levelminimum. Under an ideal situation of this control, the number ofchannels available for communication becomes the largest, while thenumber of channels available for a communication would decrease as thesituation goes away from the ideal.

Concerning a technology in controlling transmit power in a CDMA mobilecommunication, provided a transmit power controlling method described inIMT-2000 Study Committee, Air-interface WG, SWG Document Title: Volume 3Specifications of Air-Interface for 3G Mobile System, Source: SWG,Version: 0-4.0, Date: Dec. 18, 1997 issued by DENPA SANGYOUKAI, forexample (referred to as “W-CDMA mode”, hereinafter). A transmit powercontrolling method in the W-CDMA mode will be described below. In thedescription, an upstream direction means a direction of sending signalsfrom a mobile station to a base station and a downstream direction meansa direction of sending signals from a base station to a mobile station.

A base station measures a signal to interference power ratio (SIR) of asignal sent from a mobile station in the upstream direction to transmita transmit power controlling signal in accordance with the measured SIR.A structural diagram of a conventional base station is shown in FIG. 29.A signal received by an antenna 210 passes through a circulator 211 totake a process of modulating a base band signal and a process ofreceiving at a high/middle frequency in a radio module for receiving212. The base station carries out processes of synchronous capturing andreverse spreading of the received signal in synchronouscapturing/reverse spreading circuits 213 a to 213 n in which a parameteris set for each mobile station, since the received signal is a multiplexsignal from a plurality of mobile stations (referred to as MSa to MSn).The signal output from the capturing/reverse spreading circuits 213 a to213 n is input to detecting potions 214 a to 214 n, respectively, totake a detecting process such as compensation for a phase rotation. Thesignal output from the detecting portions 214 a to 214 n is input todemodulating portions 215 a to 215 n, respectively, to take an errorcontrolling process such as de-interleave and Viterbi decoding, andthen, are used as received data.

On the other hand, the signal output from the capturing/reversespreading circuits 213 a to 213 n is input to an upstream channel SIRmeasuring portion 221 through signal lines 220 a to 220 n, respectively.The upstream channel SIR measuring portion 221 measures SIR of thereceived signal input through the signal lines 220 a to 220 n,respectively (referred to as SIRa to SIRn), to input the SIRa to SIRn toan upstream channel transmit power controlling signal generating portion222 through the signal lines 230 a to 230 n.

The upstream channel transmit power controlling signal generatingportion 222 compares SIRa to SIRn with target SIRs given for MSa to MSnin advance by a controlling portion 500 (referred to as T-SIRa toT-SIRn) to generate transmit power controlling signals (TPCa to TPCn)for MSa to MSn. The controlling portion 500 is an element that controlsa whole base station and that transmits various signals to each elementin the base station. In FIG. 29, signal lines are omitted other than theline to the upstream channel transmit power controlling signalgenerating portion 222 in order to simplify the diagram. A structure ofthe controlling portion/the upstream channel transmit power controllingsignal generating portion 222 is shown in FIG. 30. The upstream channeltransmit power controlling signal generating portion 222 comprisestransmit power controlling signal generating portions 222 a to 222 nwhose inputs are SIRi and T-SIRi and whose outputs are TPCi. The addedcharacter “i” denotes one of characters “a” to “n”. A structure of atransmit power controlling signal generating portion 222 i is shown inFIG. 31. A comparator 223 i compares SIRi and T-SIRi input through asignal line 230 i to generate a signal that selects 0 in a selector 224i in the case of SIRi≧T-SIRi, and a signal that selects 1 in theselector 224 i in the case of SIRi<T-SIRi. The selector 224 i selectseither 0 or 1 in accordance with an output from the comparator 223 i tooutput it as TPCi through a signal line 231 i. The TPCi=0 is a signalthat instructs a mobile station to reduce the transmit power. On thecontrary, TPCi=1 is a signal that instructs a mobile station to increasethe transmit power.

Frame forming portions 225 a to 225 n shown in FIG. 29 form transmissiondata to MSa to Msn, the data which took an error controlling processsuch as fold-encoding and interleave in encoding portions 222 a to 222n, and the transmit power controlling signals TPCa to TPCn, which areinput from the upstream channel transmit power controlling signalgenerating portion 222, into frames in accordance with a format definedin the system. Spreading circuits 223 a to 223 n carry out a spectrumspreading process for outputs from the frame forming portions with aparameter corresponding to MSa to MSn. An adding circuit 226 addstransmission signals in order to multiplex signals for MSa to MSn. Thetransmission signals output from the adding circuit 226 are transmittedfrom the antenna 210 after passing through a radio module fortransmission 224 and a circulator 211.

A mobile station MSi receives the aforementioned transmit powercontrolling signal TPCi to change the transmit power in accordance witha result of demodulation. A structure of a conventional mobile stationis shown in FIG. 32. A signal received by the antenna 10 passes througha circulator 11 to take a process of demodulating a base band signal anda process of receiving at a high/middle frequency in a radio module forreceiving 12.

A mobile station carries out processes of synchronous capturing andspectrum reverse spreading of the received signal in a synchronouscapturing/reverse spreading circuit 13 in which a parameter is set for achannel being used in the mobile station, since the received signal is amultiplex signal in a plurality of channels. The signal output from thesynchronous capturing/reverse spreading circuit 13 takes a detectingprocess such as compensation for a phase rotation in a detecting portion14 and takes an error controlling process such as de-interleave andViterbi decoding in demodulating portion 15, so as to be used asreceived data.

After output from the detecting portion 14, the received transmit powercontrolling signal passes through a signal line 16 and is input to atransmit power controlling signal determining portion 40. The transmitpower controlling signal determining portion 40 determines whether thereceived transmit power controlling signal is “0” or “1”. The transmitpower controlling signal determining portion 40 generates a controllingsignal, which selects “−1 dB”, for example, as an output for a selector41 when the result of determining the transmit power controlling signalis “0”, and generates a controlling signal, which selects “+1 dB”, forexample, as an output for the selector 41 when the result of determiningis “1”, to send the controlling signal to the selector 41.

The selector 41 outputs either “+1 dB” or “−1 dB”, for example, as avariation amount of the transmit power in accordance with a controllingsignal input from the transmit power controlling signal determiningportion 40.

A transmit power calculating portion 19 determines the changed transmitpower, using the variation amount of the transmit power input from theselector 41 and the current transmit power input from a transmit powermaintaining circuit 20. That is, the changed transmit power is increasedby 1 dB from the current transmit power when the selector inputs “+1dB”, and it is decreased by 1 dB from the current transmit power whenthe selector contrary inputs “−1 dB”.

The transmission signal takes an error controlling process such as, forexample, fold-encoding and interleave, in the encoding portion 22 toform a frame of a format defined in the system in a frame formingportion 25, and then, takes a spectrum spreading process in a spreadingcircuit 23. A variable gain amplifier 21 amplifies transmission signalsat a proper gain so that the signals could be transmitted at thedesignated transmit power from the transmit power calculating portion19. The transmission signal output from the variable gain amplifier 21passes through the radio module for transmission 24 and the circulator11, and then, is transmitted from the antenna 10.

An example of a change of the transmit power of a mobile station in thecase that the mobile station performs the above operation is shown as asolid line 62 in FIG. 33. The horizontal axis 60 shows the time, whilethe vertical axis 61 shows the transmit power of the mobile station.Results 83 a to 83 e of determining the transmit power controllingsignal received at the times 120 to 124 are also shown in the horizontalaxis 60. As shown in FIG. 33, the mobile station operates so as toincrease the transmit power by 1 dB at the times 122 and 124 when theresult of determining the controlling signal is “1” and so as todecrease the transmit power by 1 dB at the times 120, 121 and 123 whenthe result of determining the controlling signal is “0”.

There are two problems solved by the invention as described below.

First, there is a large possibility that the received transmit powercontrolling signal would result in being demodulated with an error, whenthe quality of receiving the transmit power controlling signal in amobile station is bad. In this case, the conventional method that thedemodulated result is determined either “0” or “1” increases thepossibility that the transmit power controlling signal is incorrectlydetermined to be a value different from the proper value.

In the case that the transmit power controlling signal, which should bedetermined to be “1”, is incorrectly determined to be “0”, namely, inthe case that a mobile station incorrectly decreases the transmit powerat the time when the transmit power should be increased, the quality ofa signal received from the above mobile station would deteriorate in thebase station. This causes the quality of a communication to bedeteriorated, and furthermore, causes a communication to be cut off.

To the contrary, in the case that the transmit power controlling signal,which should be determined to be “0”, is incorrectly determined to be“1”, namely, in the case that a mobile station incorrectly increases thetransmit power at the time when the transmit power should be decreased,the interference amount by the above mobile station to another mobilestation would increase in the base station. Therefore, deterioration ofthe communication quality and cut-off of a communication occur in theother mobile station. This means, at the same time, that the number ofmobile stations available for a communication would decrease, and as aresult, the communication capacity of the whole system will be reduced.

Moreover, the aforementioned deterioration of the communication qualityand reduction of the communication capacity of the system appear moresignificantly, when the result of determining the transmit powercontrolling signal, whose receiving quality is bad, is biased to either“0” or “1” due to such as a component of direct current offset containedin a receiver in a mobile station.

Secondly, when a receiving operation stops earlier than a transmittingoperation as a controlling sequence in the base station upon cutting offa communication, that is, an operation of the synchronouscapturing/reverse spreading circuit 213 i (i=1, 2, . . . , n) stopsearlier than that of the upstream channel SIR measuring portion 221 inFIG. 29, it is considered that the operation of the upstream channel SIRmeasuring portion 221 would become unstable, since the upstream channelSIR measuring portion 221 tries to get SIRi from the output of thesynchronous capturing/reverse spreading circuit 213 i whose operationhas stopped. In this case, an improper transmit power controlling signalTPCi is generated to be transmitted from the base station to the mobilestation MSi. The mobile station MSi may perform transmission with anexcessive transmit power, as a result of controlling the transmit powerin accordance with the above-mentioned improper transmit powercontrolling signal TPCi. In this case, the interference amount by asignal of the mobile station MSi to another mobile station increases inthe base station. Thus, the deterioration of the communication qualityand cut-off of a communication occur in the other mobile station. Thisreduces the communication capacity of the whole system, like the firstproblem.

DISCLOSURE OF THE INVENTION

In order to solve the first problem, a structure according to thepresent invention is arranged so that a radio base station transmits atransmit power controlling signal for controlling transmit power of amobile station, and that said mobile station calculates a likelihood ofsaid transmit power controlling signal on the basis of the receivedtransmit power controlling signal and the receiving quality to calculatea variation amount of the transmit power on the basis of saidlikelihood, so that the transmit power of the mobile station would becontrolled on the basis of the variation amount.

Further, in order to solve the first problem, the invention ischaracterized in that said likelihood is calculated by further adding aperch receiving quality of a signal transmitted by said radio basestation; that the perch receiving quality of a signal transmitted bysaid radio base station is compared with the receiving quality of atransmit power controlling signal so that it is determined that a callis cut off in a channel being received when only the receiving qualityof the channel being received is deteriorated and it is determined thata receiving condition is no longer proper due to a mobile station beingin shade or the like when the both of the receiving qualities aredeteriorated at the same time; and that the likelihood is calculated onthe basis of a result of the determination.

In order to solve the first problem, the invention is also characterizedin that, when an absolute value of the likelihood of said transmit powercontrolling signal is large, an upper limit value and a lower limitvalue of the transmit power of a mobile station are updated andmaintained so that the transmit power of said mobile station is limitedbetween said upper limit value and said lower limit value.

In order to solve the first problem, the invention is also characterizedin that an average value of the transmit power of a mobile station iscalculated, and that the transmit power of said mobile station isswitched on the basis of the size of said likelihood so as to be saidcalculated average transmit power of the mobile station or transmitpower of the mobile station that is calculated on the basis of saidlikelihood.

In order to solve the first problem, the invention is characterized inthat open loop transmit power is calculated on the basis of thereceiving quality or the receiving power of another channel differentfrom a channel being used, and that the transmit power of said mobilestation is switched on the basis of the size of said likelihood so as tobe said calculated open loop transmit power or transmit power of themobile station that is calculated on the basis of said likelihood.

In order to solve the first problem, the invention is characterized inthat said transmit power controlling signal is a signal comprising twovalues, and that said likelihood is calculated so that an absolute valueof the likelihood would be large when the receiving quality is good andso that an absolute value of the likelihood would be small when thereceiving quality is bad.

In order to solve the first problem, the invention is characterized inthat the transmit power is increased when said likelihood is a firstreference value or more, that the transmit power is maintained when saidlikelihood is less than said first reference value and the secondreference value or more, and that the transmit power is decreased whensaid likelihood is less than said second reference value.

In order to solve the first problem, the invention is characterized inthat the transmit power is increased when said likelihood is said firstreference value or more, that the transmit power is toggle-controlledwhen said likelihood is less than said first reference value and saidsecond reference value or more, and that the transmit power is decreasedwhen said likelihood is less than said second reference value.

In order to solve the first problem, the invention is characterized inthat the transmit power is increased when said likelihood is said firstreference value or more, that a variation amount of the transmit poweris made to be the power corresponding to said likelihood when saidlikelihood is less than said first reference value and said secondreference value or more, and that the transmit power is decreased whensaid likelihood is less than said second reference value.

In order to solve the first problem, a mobile station according to theinvention comprises: receiving means for receiving transmit powercontrolling information transmitted by a radio base station; measuringmeans for measuring the receiving quality of a wave transmitted by saidradio base station; likelihood generating means for generating alikelihood of said transmit power controlling information on the basisof the transmit power controlling information received by said receivingmeans and the receiving quality measured by said measuring means;variation amount generating means for generating a variation amount ofthe transmit power on the basis of the likelihood generated by saidlikelihood generating means; and controlling means for controlling thetransmit power of a mobile station on the basis of the variation amountgenerated by said variation amount generating means.

In order to solve the first problem, a mobile station according to theinvention further comprises perch receiving quality measuring means formeasuring the receiving quality of a perch signal transmitted by saidradio base station, wherein said likelihood generating means generates alikelihood with the receiving quality measured by said perch receivingquality measuring means taken into a consideration.

In order to solve the first problem, in a communication system accordingto the invention, a radio base station comprises: transmit powercontrolling information generating means for generating transmit powercontrolling information for controlling the transmit power of a mobilestation; and transmitting means for transmitting the transmit powercontrolling information generated by said transmit power controllinginformation generating means, and a mobile station comprises: receivingmeans for receiving the transmit power controlling informationtransmitted by said transmit means; measuring means for measuring thereceiving quality of a wave transmitted by said radio base station;likelihood generating means for generating a likelihood of said transmitpower controlling information on the basis of the transmit powercontrolling information received by said receiving means and thereceiving quality measured by said measuring means; variation amountgenerating means for generating a variation amount of the transmit poweron the basis of the likelihood generated by said likelihood generatingmeans; and controlling means for controlling the transmit power of amobile station on the basis of the variation amount generated by saidvariation amount generating means.

In order to solve the second problem, the invention is characterized inthat a radio base station measures SIR for every said mobile station tocompare each of said measured SIRs with a target SIR given in advance,generates a transmit power controlling signal for decreasing thetransmit power when said SIR is the target SIR or more or when saidradio base station has stopped a receiving operation for said mobilestation, generates a transmit power controlling signal for increasingthe transmit power when said SIR is less than the target SIR, andtransmits said generated transmit power controlling signal to the mobilestation.

In order to solve the second problem, the invention is characterized bya radio base station controlling transmit power of a mobile stationcomprising: signal quality measuring means for measuring signal qualityof said mobile station; comparing means for comparing the signal qualitymeasured by said signal quality measuring means with a predeterminedvalue; generating means for generating, as a result of comparison insaid comparing means, transmit power controlling information fordecreasing said transmit power when said signal quality is saidpredetermined value or more and for generating transmit powercontrolling information for increasing said transmit power when saidsignal quality is less than said predetermined value; and transmittingmeans for transmitting to said mobile station the transmit powercontrolling signal generated by said generating means. The above signalquality is SIR or the like.

In order to solve the second problem, according to the invention, aradio base station controlling transmit power of a mobile stationcomprises: receiving means for receiving a channel transmitted by saidmobile station; controlling means for controlling a receiving operationof said receiving means; generating means for generating instructinginformation for giving an instruction to decrease the transmit power ofsaid mobile station at the time when said controlling means stops thereceiving operation of said receiving means; and transmitting means fortransmitting to said mobile station the instructing informationgenerated by said generating means.

In order to solve the second problem, according to the invention, aradio base station controlling transmit power of a mobile stationcomprises: receiving means for receiving a channel transmitted by saidmobile station; controlling means for controlling a receiving operationof said receiving means; generating means for generating instructinginformation for giving an instruction to decrease the transmit power ofsaid mobile station when said controlling means tries to stop thereceiving operation of said receiving means; and transmitting means fortransmitting to said mobile station the instructing informationgenerated by said generating means before said receiving operation isstopped.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a structure of a mobile station according to the invention.

FIG. 2 shows a structure of a transmit power controlling signallikelihood calculating portion according to the invention.

FIG. 3 shows a likelihood calculating method according to the invention.

FIG. 4 shows a structure of a transmit power variation amountcalculating portion according to the invention.

FIG. 5 shows an example of an operation of a likelihood determiningportion according to the invention.

FIG. 6 shows an example of a change of transmit power of a mobilestation according to the invention.

FIG. 7 shows a structure of a transmit power variation amountcalculating portion according to the invention.

FIG. 8 illustrates an operation of a toggle portion according to theinvention.

FIG. 9 illustrates an operation of a likelihood determining portionaccording to the invention.

FIG. 10 shows an example of a change of transmit power of a mobilestation according to the invention.

FIG. 11 shows a structure of a transmit power variation amountcalculating portion according to the invention.

FIG. 12 illustrates an operation of a transmit power variation amountcalculating portion according to the invention.

FIG. 13 shows an example of a change of transmit power of a mobilestation according to the invention.

FIG. 14 shows a structure of a mobile station according to theinvention.

FIG. 15 shows a structure of a transmit power variation amountcalculating portion according to the invention.

FIG. 16 illustrates an operation of a likelihood determining portionaccording to the invention.

FIG. 17 shows a structure of a transmit power controlling portionaccording to the invention.

FIG. 18 shows a structure of a transmit power limit value calculatingportion according to the invention.

FIG. 19 shows an example of a change of transmit power according to theinvention.

FIG. 20 shows a structure of a mobile station according to theinvention.

FIG. 21 shows a structure of a transmit power selecting portionaccording to the invention.

FIG. 22 illustrates an operation of a likelihood determining portionaccording to the invention.

FIG. 23 shows a structure of a transmit power selecting portionaccording to the invention.

FIG. 24 shows a structure of a likelihood selecting portion according tothe invention.

FIG. 25 shows a structure of a base station according to the invention.

FIG. 26 shows a structure of an upstream channel transmit powercontrolling signal generating portion according to the invention.

FIG. 27 shows a structure of the transmit power controlling signalgenerating portion according to the invention.

FIG. 28 illustrates an operation of a selector 235 i according to theinvention.

FIG. 29 shows a structure of a conventional base station.

FIG. 30 shows a structure of an upstream channel transmit powercontrolling signal generating portion according to the invention.

FIG. 31 shows a structure of a conventional transmit power controllingsignal generating portion.

FIG. 32 shows a structure of a conventional mobile station.

FIG. 33 shows a conventional varying state of transmit power.

FIG. 34 shows a structure of a receiving quality calculating portionusing perch receiving quality.

FIG. 35 shows a communication system to which the present invention isapplied.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 35 shows a communication system according to the present invention.The communication system according to the invention includes a basestation 3500 and mobile stations 3501 to 3503. The mobile station 3501is located close to the base station 3500 with its line state stable, sothat an error of power controlling bit would be few and powercontrolling would not be out of control. The mobile station 3502,however, has an obstacle 3504 such as a building on the way to the basestation 3500, although it is located close to the base station.Therefore, the obstacle 3504 greatly attenuates the wave from the basestation 3500, which may cause an error of the power controlling bit andthe power control to be out of control. Further, the mobile station 3503is located far away from the base station 3500, so that attenuation orinterference of the wave may cause an error of the power controlling bitand the power control to be out of control. The invention provides amuch more stable communication system, in which the power control itselfwould not be out of control even when a mobile station is in a conditionthat an error of the power controlling bit easily occurs.

FIG. 1 shows a structure of a mobile station of a first embodiment.Elements corresponding to those of a conventional mobile station shownin FIG. 32 are marked with the same reference number.

A received signal is processed in an antenna 10, a circulator 11, aradio module for receiving 12, a synchronous capturing/reverse spreadingcircuit 13 and a detecting portion 14, respectively, before being inputto a transmit power controlling signal likelihood calculating portion 30via a signal line 16.

The transmit power controlling signal likelihood calculating portion 30calculates likelihood of a transmit power controlling signal on thebasis of the receiving quality of the received transmit powercontrolling signal and a determined result of “0” or “1”. A structure ofthe transmit power controlling signal likelihood calculating portion 30is shown in FIG. 2. A transmit power controlling signal 0/1 determiningportion 40 determines whether the received transmit power controllingsignal is “0” or “1”.

A receiving quality calculating portion 50 calculates the receivingquality of the received transmit power controlling signal to output itto a likelihood calculating portion 51. Basically, the receiving power,SIR, or the like, which is measured on the instant upon receiving thetransmit power controlling signal, should be used as receiving qualitycalculated by the receiving quality calculating portion 50. On the otherhand, a long time integral operation is required to accurately observethe receiving power or the SIR. In the case that the above-mentionedreceiving power or the SIR integrated for a long time (referred to as along time integral value, hereinafter) is used for transmit powercontrolling, which is required to be performed at high speed, it isconsidered that the controlling delay would be increased, so that thetransmit power cannot properly controlled. Therefore, the receivingquality calculating portion 50 calculates the receiving quality of thetransmit power controlling signal, using the above transmit powercontrolling signal and the result of integrating the receiving power orthe SIR of a signal received at the time close to receiving the abovetransmit power controlling signal (referred to as a short time integralvalue, hereinafter).

Using the short time integral value may cause an incorrect calculationof the receiving quality when the short time integral value is used forcalculating the receiving quality as it is, since an error of the shorttime integral value is considered to be large. Therefore, the receivingpower calculating portion 50 may compare the long time integral valuewith the short time integral value, for example, so as to output the badreceiving quality when the difference of the both values is large.

The receiving quality calculating portion 50 also may perform thefollowing operation in order to estimate that a receiving condition of achannel being received is no longer proper due to cutting off a call orbeing in shade. A mobile station measures the receiving power or SIR ofa channel, which is always transmitted from the base station like aperch channel in the W-CDMA mode, for example, and whose transmit poweris known (referred to as perch receiving quality, hereinafter). Astructure of the receiving quality calculating portion in this case isshown in FIG. 34. A perch receiving quality measuring portion 300measures the above perch receiving quality. A comparing portion 301compares the above-mentioned short time integral value and the perchreceiving quality obtained by the perch receiving quality measuringportion 300. A receiving quality determining portion 302 determines, inaccordance with a comparing result at the comparing portion 301, that acall has been cut off in the channel being received when only thereceiving quality of the channel being received is deteriorated, andthat the receiving condition is no longer proper due to such a situationthat a mobile station is in shade when the both is deteriorated at thesame time, and then, outputs a bad receiving quality.

The likelihood calculating portion 51 calculates the likelihood of theabove transmit power controlling signal on the basis of the result ofdetermining in the transmit power controlling signal 0/1 determiningportion 40 and the result of calculating in the receiving qualitycalculating portion 50. An example of a relation between the likelihoodand the results of determining in the transmit power controlling signal0/1 determining portion 40 and of calculating in the receiving qualitycalculating portion 50 is shown by a bent line 150 in FIG. 3. The resultof calculating the likelihood shown in FIG. 3 will be described below.It is defined that the likelihood is a positive value when the result ofdetermining the transmit power controlling signal is 1. On the otherhand, it is defined that the likelihood is a negative value when theresult of determining is 0. Further, it is defined that an absolutevalue of the likelihood is large when the receiving quality is good,while the absolute value of the likelihood is small when the receivingquality is bad.

The likelihood of the transmit power controlling signal calculated inthe above method is input to a transmit power variation amountcalculating portion 31 in FIG. 1. The transmit power variation amountcalculating portion 31 calculates the variation amount of the transmitpower on the basis of the likelihood of the input transmit powercontrolling signal. A structure of the transmit power variation amountcalculating portion 31 in the first embodiment is shown in FIG. 4. Alikelihood determining portion 70 generates a controlling signal forselecting either “+1 dB (increase)”, “−1 dB (decrease)” or “0 dB (nochange)”, for example, as the variation amount of the transmit power onthe basis of the likelihood of the transmit power controlling signalinput from the transmit power controlling signal likelihood calculatingportion 30 to output the generated signal to a selector 71. An exampleof an operation of the likelihood determining portion 70 in the firstembodiment is shown in FIG. 5. The likelihood determining portion 70outputs to the selector 71 a controlling signal such that “+1 dB” isselected in the selector 71, when the likelihood of the transmit powercontrolling signal to be input exists within an area 100, which is α+ ormore. Similarly, the likelihood determining portion 70 outputs to theselector 71 a controlling signal such that “0 dB” is selected, when thelikelihood of the transmit power controlling signal to be input existswithin an area 101, which is α− or more and less than α+, and thelikelihood determining portion 70 outputs a controlling signal such that“−1 dB” is selected, when the likelihood of the transmit powercontrolling signal to be input exists within an area 102, which is lessthan α−. The selector 71 selects the transmit power variation amount inaccordance with the controlling signal from the likelihood determiningportion 70 to output the variation amount to the transmit powercalculating portion 19 shown in FIG. 1.

The transmit power calculating portion 19 shown in FIG. 1 calculates thetransmit power, as same as the case of the conventional mobile station,on the basis of the variation amount of the transmit power input fromthe transmit power variation amount calculating portion 31 and of thecurrent transmit power input from the transmit power maintaining circuit20. The transmission signal processed in the encoding portion 22 and thespreading circuit 23 is amplified so as to be transmitted at theaforementioned transmit power in the variable gain amplifier 21, andthen, passes through the radio module for transmission 24 and thecirculator 11 to be transmitted from the antenna 10.

An example of a change of transmit power of a mobile station in the casethat the mobile station performs an operation in the first embodiment isshown as a solid line 63 in FIG. 6. As shown in FIG. 6, the mobilestation operates so that the variation amount of the transmit powerwould be 0 dB, that is, the transmit power would not be changed, for atime 103 in which the likelihood of the transmit power controllingsignal is α− or more and less than α+.

Next, an operation of a mobile station of the second embodiment will bedescribed. A structure of the mobile station in the second embodiment isshown in FIG. 1 as same as that in the first embodiment. In the secondembodiment, a structure of the transmit power variation amountcalculating portion 31 is different from that of the first embodiment.The structure of the transmit power variation amount calculating portion31 in the second embodiment is shown in FIG. 7. Elements correspondingto those of the transmit power variation amount calculating portion 31in the first embodiment are marked with the same reference number.

The likelihood determining portion 70 generates a controlling signal forselecting either “+1 dB (increase)”, “−1 dB (decrease)” or “toggleportion 72 (toggle operation)”, for example, as a variation amount ofthe transmit power on the basis of the likelihood of the transmit powercontrolling signal input from the transmit power controlling signallikelihood calculating portion 30 to output the generated signal to theselector 71. An operation of the toggle portion 72 is shown in FIG. 8.

The toggle portion 72 outputs “−1 dB” in the case of the input of “+1dB”, and “+1 dB” in the case of the input of “−1 dB”. An example of anoperation of the likelihood determining portion 70 in the secondembodiment is shown in FIG. 9. The likelihood determining portion 70outputs to the selector 71 a controlling signal such that “+1 dB” isselected in the selector 71, when the likelihood of the transmit powercontrolling signal to be input exists within an area 100, which is α+ ormore. Similarly, the likelihood determining portion 70 outputs to theselector 71 a controlling signal such that “toggle portion 72” isselected, when the likelihood of the transmit power controlling signalto be input exists within an area 101, which is α− or more and less thanα+, and the likelihood determining portion 70 outputs a controllingsignal such that “−1 dB” is selected, when the likelihood of thetransmit power controlling signal to be input exists within an area 102,which is less than α−.

The selector 71 selects the transmit power variation amount inaccordance with the controlling signal from the likelihood determiningportion 70 to output the variation amount to the transmit powercalculating portion 19 shown in FIG. 1. The operation thereafter to thetransmission of the transmission signal from the antenna 10 is same asthat of the first embodiment.

An example of a change of transmit power of a mobile station in the casethat a mobile station performs an operation in the second embodiment isshown as a solid line 64 in FIG. 10. As shown in FIG. 10, the mobilestation operates so that the variation amount of the transmit powerwould repeat “+1 dB” and “−1 dB” alternately, during a time 103 in whichthe likelihood of the transmit power controlling signal is α− or moreand less than α+.

Next, an operation of a mobile station of the third embodiment will bedescribed. A structure of the mobile station in the third embodiment isshown in FIG. 1 as same as the first and second embodiments. In thethird embodiment, a structure of the transmit power variation amountcalculating portion 31 is different from that of the first and secondembodiments. The structure of the transmit power variation amountcalculating portion 31 in the third embodiment is shown in FIG. 11. Alikelihood-transmit power variation amount converting portion 73converts the likelihood of the transmit power controlling signal inputfrom the transmit power controlling signal likelihood calculatingportion 30 into the transmit power variation amount. An example of anoperation of the likelihood-transmit power variation amount convertingportion 73 is shown as a line 74 in FIG. 12. In FIG. 12, thelikelihood-transmit power variation amount converting portion 73 outputs“+1 dB”, for example, to the transmit power calculating portion 19 as atransmit power variation amount, when the likelihood of the transmitpower controlling signal to be input is α+ or more. Similarly, thelikelihood-transmit power variation amount converting portion 73 outputs“−1 dB”, for example, to the transmit power calculating portion 19 as atransmit power variation amount, when the likelihood of the transmitpower controlling signal to be input is less than α−. Thelikelihood-transmit power variation amount converting portion 73 outputsa transmit power variation amount, which varies as shown as the line 74in FIG. 12, for example, to the transmit power calculating portion 19 inaccordance with the likelihood of the transmit power controlling signal.The operation thereafter to the transmission of the transmission signalfrom the antenna 10 is same as that of the first embodiment.

An example of a change of transmit power of a mobile station in the casethat the mobile station performs an operation in the third embodiment isshown as a solid line 65 in FIG. 13. As shown in FIG. 13, the mobilestation controls the transmit power so that the variation amount of thetransmit power would be a value smaller than “+1 dB”and “−1 dB” duringthe time 103 in which the likelihood of the transmit power controllingsignal is α− or more and less than α+.

A structure of the mobile station in the fourth embodiment is shown inFIG. 14. Elements corresponding to a structure of the mobile stationsshown in FIGS. 32 and 1 are marked with the same reference number. Thelikelihood of the transmit power controlling signal calculated in thetransmit power controlling signal likelihood calculating portion 30 isinput to the transmit power variation amount calculating portion 31, assame as in the first embodiment.

A structure of the transmit power variation amount calculating portion31 in the fourth embodiment is shown in FIG. 15. The likelihooddetermining portion 130 generates a controlling signal for selectingeither “+1 dB (increase)” or “−1 dB (decrease)”, for example, as avariation amount of the transmit power on the basis of the likelihood ofthe transmit power controlling signal input from the transmit powercontrolling signal likelihood calculating portion 30 to output thegenerated signal to a selector 131. An example of an operation of thelikelihood determining portion 130 in the fourth embodiment is shown inFIG. 16. The likelihood determining portion 130 outputs to the selector131 a controlling signal such that “+1 dB” is selected in the selector131, when the likelihood of the transmit power controlling signal to beinput exists within an area of 0 or more. On the other hand, thelikelihood determining portion 130 outputs to the selector 131 acontrolling signal such that “−1 dB” is selected, when the likelihood ofthe transmit power controlling signal to be input exists within an arealess than 0. The selector 131 selects the transmit power variationamount in accordance with the controlling signal from the likelihooddetermining portion 130 to output the variation amount to the transmitpower calculating portion 19 shown in FIG. 14. The transmit powercalculating portion 19 calculates the transmit power of the mobilestation as same as in the first embodiment.

The transmit power limiting portion 32 compares the transmit powercalculated in the transmit power calculating portion 19 and the transmitpower limit value calculated inside the transmit power limiting portion32 to control the transmit power of the mobile station. A structure ofthe transmit power limiting portion 32 is shown in FIG. 17. The transmitpower input from the transmit power calculating portion 19 is input to atransmit power limit value calculating portion 90 and a comparingportion 91. An example of an operation of the transmit power limit valuecalculating portion 90 is shown in FIG. 18. In the transmit power limitvalue calculating portion 90, the likelihood of the transmit powercontrolling signal input from the transmit power controlling signallikelihood calculating portion 30 is first compared with thresholds β−and β+. When the likelihood of the transmit power controlling signalcannot establish a relation β−≦(likelihood)<β+, that is, when theabsolute value of the likelihood of the transmit power controllingsignal is large, the upper limit value TXPU of the transmit power andthe lower limit value TXPL of the transmit power are updated. Accordingto this operation, the upper and lower limit values of the transmitpower of the mobile station are calculated when the absolute value ofthe likelihood of the transmit power controlling signal is large, thatis, when the receiving quality of the transmit power controlling signalis good, while the upper and lower limit values of the transmit power ofthe mobile station are maintained when the absolute value of thelikelihood of the transmit power controlling signal is small, that is,when the receiving quality of the transmit power controlling signal isbad.

The comparing portion 91 shown in FIG. 17 compares the transmit powerinput from the transmit power calculating portion 19 and the upper andlower limit values of the transmit power input from the transmit powerlimit value calculating portion 90. The comparing portion 91 changes thetransmit power into TXPU to output it to the transmit power maintainingcircuit 20 and the variable gain amplifier 21 shown in FIG. 14, when thetransmit power input from the transmit power calculating portion 19 islarger than the upper limit value TXPU of the transmit power input fromthe transmit power limit value calculating portion 90. On the otherhand, the comparing portion 91 changes the transmit power into TXPL tooutput it to the transmit power maintaining circuit 20 and the variablegain amplifier 21 shown in FIG. 14, when the transmit power input fromthe transmit power calculating portion 19 is smaller than the lowerlimit value TXPL of the transmit power input from the transmit powerlimit value calculating portion 90. Further, the comparing portion 91outputs the transmit power input from the transmit power calculatingportion 19 to the transmit power maintaining. circuit 20 and thevariable gain amplifier 21 shown in FIG. 14, as it is, when the transmitpower input from the transmit power calculating portion 19 is betweenTXPU and TXPL. The operation thereafter to the transmission of thetransmission signal from the antenna 10 is same as that of the firstembodiment.

An example of a change of transmit power of a mobile station in the casethat the mobile station performs an operation in the fourth embodimentis shown as a solid line 66 in FIG. 19. As shown in FIG. 19, the upperlimit value TXPU and the lower limit value TXPL of the transmit power ofthe mobile station are maintained at a certain value during the time 103in which the likelihood of the transmit power controlling signal is α−or more and less than α+. In the example shown in FIG. 19, the transmitpower of the mobile station is limited not so as to be less than thelower value TXPL of the transmit power during the time 103.

In the fourth embodiment, the transmit power variation amountcalculating portion 31 may have a structure shown in the first to thirdembodiments.

A structure of a mobile station in the fifth embodiment is shown in FIG.20. Elements corresponding to a structure of the mobile stations shownin FIGS. 32 and 1 are marked with the same reference number. Thelikelihood of the transmit power controlling signal calculated in thetransmit power controlling signal likelihood calculating portion 30 isinput to the transmit power variation amount calculating portion 31, assame as in the first embodiment. The transmit power variation amountcalculating portion 31 may have any structure and operation of thetransmit power variation amount calculating portion 31 described in thefirst to fourth embodiments. The variation amount of the transmit powercalculated in the transmit power variation amount calculating portion 31is input to the transmit power calculating portion 19.

The transmit power calculating portion 19 calculates the transmit powerof the mobile station as same as in the first embodiment.

The transmit power calculated in the transmit power calculating portion19 is input to a transmit power selecting portion 33. The transmit powerselecting portion 33 selects the transmit power in accordance with thelikelihood of the transmit power controlling signal input from thetransmit power controlling signal likelihood calculating portion 30.

A structure of the transmit power selecting portion 33 in the fifthembodiment is shown in FIG. 21. A likelihood determining portion 140generates a controlling signal for selecting as the transmit powereither the transmit power input from the transmit power calculatingportion 19 or the transmit power input from a transmit power averagingportion. 142 on the basis of the likelihood of the transmit powercontrolling signal input from the transmit power controlling signallikelihood calculating portion 30, and outputs the generated signal to aselector 141. An example of an operation of the likelihood determiningportion 140 in the fifth embodiment is shown in FIG. 22. The likelihooddetermining portion 140 outputs to the selector 141 a controlling signalsuch that the transmit power input from the transmit power calculatingportion 19 is selected in the selector 141, when the likelihood of thetransmit power controlling signal to be input exists within an area 104,which is γ+ or more, or an area 106, which is less than γ−, namely, whenthe receiving quality of the received transmit power controlling signalis good. On the other hand, the likelihood determining portion 140outputs to the selector 141 a controlling signal such that the transmitpower input from the transmit power averaging portion 142 is selected,when the likelihood of the transmit power controlling signal to be inputexists within an area 105, which is γ− or more and less than γ+, namely,when the receiving quality of the received transmit power controllingsignal is bad. The selector 141 selects the transmit power in accordancewith the controlling signal from the likelihood determining portion 140to output the transmit power to a transmit power maintaining circuit 20and a variable gain amplifier 21 shown in FIG. 20. The transmit poweraveraging portion 142 calculates an average value of the transmit powerto be input so as to output the average value to the selector 141.

The operation thereafter to the transmission of the transmission signalfrom the antenna 10 is same as that of the first embodiment.

Next, an operation of a mobile station of the sixth embodiment will bedescribed. A structure of the mobile station in the sixth embodiment isshown in FIG. 20 as same as that in the fifth embodiment. In the sixthembodiment, a structure of the transmit power selecting portion 33 isdifferent from that of the fifth embodiment. The structure of thetransmit power selecting portion 33 in the sixth embodiment is shown inFIG. 23. A likelihood determining portion 150 generates a controllingsignal for selecting as the transmit power either the transmit powerinput from the transmit power calculating portion 19 or the transmitpower input from an open loop transmit power calculating portion 152 onthe basis of the likelihood of the transmit power controlling signalinput from the transmit power controlling signal likelihood calculatingportion 30, and outputs the generated signal to a selector 151. Anexample of an operation of the likelihood determining portion 150 in thesixth embodiment is shown in FIG. 24. The likelihood determining portion150 outputs to the selector 151 a controlling signal such that thetransmit power input from the transmit power calculating portion 19 isselected in the selector 151, when the likelihood of the transmit powercontrolling signal to be input exists within an area 107, which is δ+ ormore, or an area 109, which is less than δ−, namely, when the receivingquality of the received transmit power controlling signal is good.

On the other hand, the likelihood determining portion 150 outputs to theselector 151 a controlling signal such that the transmit power inputfrom the open loop transmit power calculating portion 152 is selected,when the likelihood of the transmit power controlling signal to be inputexists within an area 108, which is δ− or more and less than δ+, namely,when the receiving quality of the received transmit power controllingsignal is bad. The selector 151 selects the transmit power in accordancewith the controlling signal from the likelihood determining portion 150to output the transmit power to the transmit power maintaining circuit20 and the variable gain amplifier 21 shown in FIG. 20.

The open loop transmit power calculating portion 152 uses the receivingquality, the receiving power and the like of a channel different fromthe channel being used for a communication such as a perch channel inthe W-CDMA mode, for example, so as to estimate the attenuation amountbetween a mobile station and a base station, and calculates the transmitpower of the mobile station, which meets the receiving quality requiredin the base station. The open loop transmit power calculating portion152 outputs the calculated transmit power to the selector 151.

The operation thereafter to the transmission of the transmission signalfrom the antenna 10 is same as that of the first embodiment.

A structure of a base station in the seventh embodiment is shown in FIG.25. Elements corresponding to a structure of a conventional base stationshown in FIG. 29 are marked with the same reference number. A receivedsignal is measured for SIR (SIRa to SIRn) per a mobile station (MSa toMSn) in the upstream channel SIR measuring portion 221 to be inputthrough signal lines 230 a to 230 n into an upstream channel transmitpower controlling signal generating portion 250 as same as in theconventional base station.

The upstream channel transmit power controlling signal generatingportion 250 generates a transmit power controlling signal for MSa to MSn(referred to as TPCa to TPCn) on the basis of a comparison resultbetween SIRa to SIRn and a target SIR, which is given in advance from acontrolling portion 501 for MSa to MSn (referred to as T-SIRa toT-SIRn), and of RXa to RXn, which are a controlling signal showingwhether a receiving operation is performed for a signal transmitted fromthe MSa to MSn and which are input from the controlling portion 501. Thecontrolling portion 501 is further provided with a function forsupplying the upstream channel transmit power controlling signalgenerating portion 250 with RXa to RXn, in addition to a function sameas the controlling portion 500 of the conventional base station shown inFIG. 29. When a normal communication is carried out between MSi (i=a, .. . , n) and the base station, RXi (i=a, . . . , n) is a signal whosecontent indicates that a receiving operation is going on for the signaltransmitted from MSi. On the other hand, when a normal communicationcannot be maintained between MSi and the base station due to aninfluence of such as being in shade, so that the base station stopsreceiving a signal from MSi, RXi is a signal whose content indicatesthat the receiving operation is not performed for the signal transmittedfrom MSi.

A structure of the upstream channel transmit power controlling signalgenerating portion 250 is shown in FIG. 26. The upstream channeltransmit power controlling signal generating portion 250 comprisestransmit power controlling signal generating portions 250 a to 250 nwhose inputs are SIRi, T-SIRi and RXi and whose outputs are TPCi. Theadded character “i” denotes one of characters “a” to “n”. A structure ofa transmit power controlling signal generating portion 250 i is shown inFIG. 27. A comparator 254 i compares SIRi input through a signal line230 i and T-SIRi to generate a signal that selects 0 (a signalinstructing to decrease the transmit power) in a selector 251 i in thecase of SIRi≧T-SIRi, and a signal that selects 1 (a signal instructingto increase the transmit power) in the selector 251 i in the case ofSIRi<T-SIRi. The selector 251 i selects 0 or 1 in accordance with anoutput from the comparator 254 i to output it through a signal line 252i to a selector 253 i. The selector 253 i determines the transmit powercontrolling signal TPCi in accordance with the signal RXi indicatingwhether a receiving operation is going on or not. An operation of theselector 253 i is shown in FIG. 28. The selector 253 i selects a signalinput as the transmit power controlling signal TPCi through a signalline 252 i, when RXi is a signal indicating that a receiving operationis going on. On the contrary, the selector 253 i selects 0 (a signalinstructing to decrease the transmit power) as the transmit powercontrolling signal TPCi when RXi is a signal indicating that a receivingoperation has been stopped.

The transmit power controlling signals TPCa to TPCn for MSa to MSngenerated in the above method are input through signal lines 231 a to231 n into frame forming portions 225 a to 225 n to take processessimilar to the case of the conventional base station before beingtransmitted from the antenna 210.

A mobile station according to the invention does not cause an error incontrolling the transmit power even in the case of receiving thetransmit power controlling signal, which includes an error in receiving.That is, transmission at excessive transmit power due to incorrectcontrol or out-of control can be prevented, so that the number ofsubscribers contained in a system can be increased, compared with theconventional case. Further, the power supply of a mobile station can besaved since the transmission is not carried out at excessive transmitpower.

According to the radio base station according to the invention, it canbe possible to prevent a mobile station from transmitting at excessivetransmit power by controlling the mobile station not to transmit animproper transmit power controlling signal after stopping a receivingoperation for the signal to be transmitted. Thus, deterioration of thecommunication quality due to an error in controlling power can beavoided and the subscriber capacity of a whole system can besignificantly improved.

1. A transmit power controlling method in a code division multiple access communication system which includes a radio base station and a mobile station, said method comprising the steps of: transmitting, by said radio base station, a transmit power controlling signal for controlling transmit power of said mobile station; and generating, by said mobile station, a reference value for calculating a control amount of transmit power of said mobile station based on the transmit power controlling signal received from said radio base station and the receiving quality of the transmit power controlling signal, and generating a variation amount of the transmit power based on said reference value, so that the transmit power of said mobile station is controlled based on the variation amount.
 2. The transmit power controlling method in a code division multiple access communication system according to claim 1, wherein said reference value is generated with a perch channel receiving quality of a signal transmitted from said radio base station also taken into account.
 3. The transmit power controlling method in a code division multiple access communication system according to claim 1, wherein the receiving quality of a perch channel signal transmitted from said radio base station is compared with the receiving quality of the transmit power controlling signal so that it is determined that a call is cut off when only one of the receiving qualities is deteriorated and it is determined that a receiving condition is no longer proper when the both of the receiving qualities are deteriorated, and in that the reference value is generated based on a result of the determination.
 4. The transmit power controlling method in a code division multiple access communication system according to claim 1, wherein, when an absolute value of the reference value of said transmit power controlling signal is larger than a predetermined value, an upper limit value and a lower limit value of the transmit power of a mobile station are updated and maintained so that the transmit power of said mobile station is limited between said upper limit value and said lower limit value.
 5. The transmit power controlling method in a code division multiple access communication system according to claim 1, wherein an average value of the transmit power of a mobile station is generated, and that the transmit power of said mobile station is switched based on the size of said reference value so as to be either said generated average transmit power of the mobile station or transmit power of the mobile station that is generated based on said reference value.
 6. The transmit power controlling method in a code division multiple access communication system according to claim 1, wherein an open loop transmit power signal is generated based on the receiving quality or the receiving power of another channel different from a channel being used, and that the transmit power of said mobile station is switched based on the size of said reference value so as to be a transmit power based on the generated open loop transmit power controlling signal or transmit power based on the generated reference value.
 7. The transmit power controlling method in a code division multiple access communication system according to claim 1, wherein said transmit power controlling signal is a signal comprising two values, and that said reference value is calculated so that an absolute value of the reference value would be larger than a predetermined value when the receiving quality is better than a predetermined quality and so that an absolute value of the reference value would be smaller than a predetermined value when the receiving quality is worse than a predetermined quality.
 8. The transmit power controlling method in a code division multiple access communication system according to claim 7, wherein the transmit power is increased when said reference value is greater than or equal to a first reference value, wherein the transmit power is maintained when said reference value is greater than or equal to a second reference value, and wherein the transmit power is decreased when said reference value is less than said second reference value.
 9. The transmit power controlling method in a code division multiple access communication system according to claim 7, wherein the transmit power is increased when said reference value is greater than or equal to said first reference value, wherein the transmit power is toggle-controlled when said reference value is greater than or equal to said second reference value, and wherein the transmit power is decreased when said reference value is less than said second reference value.
 10. The transmit power controlling method in a code division multiple access communication system according to claim 7, wherein the transmit power is increased when said reference value is greater than or equal to said first reference value, that a variation amount of the transmit power is made to be the power corresponding to said reference value when said reference value is greater than or equal to said second reference value, and wherein the transmit power is decreased when said reference value is less than said second reference value.
 11. A mobile station characterized by comprising: receiving means for receiving transmit power controlling information transmitted by a radio base station; measuring means for measuring the receiving quality of a wave transmitted by said radio base station; reference value generating means for generating a reference value for calculating a control amount of transmit power for said mobile station based on the transmit power controlling information received by said receiving means from said radio base station and the receiving quality measured by said measuring means; variation amount generating means for generating a variation amount of the transmit power based on the reference value generated by said reference value generating means; and controlling means for controlling the transmit power of a mobile station based on the variation amount generated by said variation amount generating means.
 12. The mobile radio station according to claim 11, further comprising: perch channel receiving quality measuring means for measuring the receiving quality of a perch channel signal transmitted by said radio base station, wherein said reference value generating means generates a reference value with the receiving quality measured by said perch channel signal receiving quality measuring means taken into a consideration.
 13. A code division multiple access communication system comprising: a radio base station; and a mobile station, wherein said radio base station comprises: transmit power controlling information generating means for generating transmit power controlling information for controlling the transmit power of a mobile station, and transmitting means for transmitting the transmit power controlling information generated by said transmit power controlling information generating means, and wherein said mobile station comprises: receiving means for receiving the transmit power controlling information transmitted by said transmitting means, measuring means for measuring the receiving quality of a wave transmitted by said radio base station, reference value generating means for generating a reference value for calculating a control amount of transmit power for said mobile station based on the transmit power controlling information received by said receiving means and the receiving quality measured by said measuring means, variation amount generating means for generating a variation amount of the transmit power based on the reference value generated by said reference value generating means, controlling means for controlling the transmit power of a mobile station based on the variation amount generated by said variation amount generating means. 